# MicroPython SSD1306 OLED驱动，I2C接口
from micropython import const
import framebuf

# 寄存器定义
SET_CONTRAST = const(0x81)
SET_ENTIRE_ON = const(0xA4)
SET_NORM_INV = const(0xA6)
SET_DISP = const(0xAE)
SET_MEM_ADDR = const(0x20)
SET_COL_ADDR = const(0x21)
SET_PAGE_ADDR = const(0x22)
SET_DISP_START_LINE = const(0x40)
SET_SEG_REMAP = const(0xA0)
SET_MUX_RATIO = const(0xA8)
SET_COM_OUT_DIR = const(0xC0)
SET_DISP_OFFSET = const(0xD3)
SET_COM_PIN_CFG = const(0xDA)
SET_DISP_CLK_DIV = const(0xD5)
SET_PRECHARGE = const(0xD9)
SET_VCOM_DESEL = const(0xDB)
SET_CHARGE_PUMP = const(0x8D)

class SSD1306_I2C(framebuf.FrameBuffer):
    def __init__(self, width, height, i2c, addr=0x3C, external_vcc=False):
        self.width = width
        self.height = height
        self.external_vcc = external_vcc
        self.pages = height // 8
        self.buffer = bytearray(self.pages * width)
        super().__init__(self.buffer, width, height, framebuf.MONO_VLSB)
        self.i2c = i2c
        self.addr = addr
        self.init_display()

    def init_display(self):
        cmds = [
            SET_DISP | 0x00,  # 关闭显示
            SET_MEM_ADDR, 0x00,  # 水平寻址模式
            SET_DISP_START_LINE | 0x00,
            SET_SEG_REMAP | 0x01,  # 列地址127映射到SEG0
            SET_MUX_RATIO, self.height - 1,
            SET_COM_OUT_DIR | 0x08,  # 从COM[N-1]到COM0扫描
            SET_DISP_OFFSET, 0x00,
            SET_COM_PIN_CFG, 0x02 if self.width > 2 * self.height else 0x12,
            SET_DISP_CLK_DIV, 0x80,
            SET_PRECHARGE, 0x22 if self.external_vcc else 0xF1,
            SET_VCOM_DESEL, 0x30,  # 0.83*Vcc
            SET_CONTRAST, 0xFF,  # 最大对比度
            SET_ENTIRE_ON,  # 输出跟随RAM内容
            SET_NORM_INV,  # 正常显示
            SET_CHARGE_PUMP, 0x10 if self.external_vcc else 0x14,
            SET_DISP | 0x01  # 开启显示
        ]
        for cmd in cmds:
            self.write_cmd(cmd)
        self.fill(0)
        self.show()

    def write_cmd(self, cmd):
        self.i2c.writeto(self.addr, bytearray([0x80, cmd]))

    def write_data(self, buf):
        self.i2c.writeto_mem(self.addr, 0x40, buf)

    def show(self):
        x0 = 0
        x1 = self.width - 1
        if self.width == 64:
            x0 += 32
            x1 += 32
        self.write_cmd(SET_COL_ADDR)
        self.write_cmd(x0)
        self.write_cmd(x1)
        self.write_cmd(SET_PAGE_ADDR)
        self.write_cmd(0)
        self.write_cmd(self.pages - 1)
        self.write_data(self.buffer)
